Laser beam welding of aluminum to Al-base coated high-strength steel 22MnB5

The microstructure of aluminum-Al-coated steel laser beam welding joints was analyzed with respect to the welding energy. Quantitative and qualitative analysis of the welding microstructure were used to measure the weld width as well as the thickness of the resulting intermetallic layer at the 22MnB5/aluminum interface in relation to the welding parameters. Weldability of Al-coated steel could be improved by removing brittle coating particles and oxides on the steel surface by sandblasting. Adhesion of aluminum filler material to the 22MnB5 steel sheet could be enhanced by inductive preheating of the steel surface during laser welding. This produced welded 22MnB5/aluminum joints that exhibited a linear mechanical resistance of 220 MPa and which failed away from the brittle intermetallic layer on the aluminum side under a tensile load. The shear strength of the intermetallic layer on the 22MnB5/aluminum interface was evaluated to 74 ± 21 MPa.